Fast response pedestal assembly for selective preclean

ABSTRACT

Implementations of the present disclosure generally relate to an improved substrate support pedestal assembly. In one implementation, the substrate support pedestal assembly includes a shaft. The substrate support pedestal assembly further includes a substrate support pedestal, mechanically coupled to the shaft. The substrate support pedestal comprises substrate support plate coated on a top surface with a ceramic material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Application Serial No.15/934,415, filed Mar. 23, 2018, which claims benefit of U.S.Provisional Pat. Application No. 62/638,716, filed Mar. 5, 2018, each ofwhich is incorporated herein by reference in its entirety.

FIELD

Implementations of the present disclosure generally relate to a pedestalfor use in precleaning chamber and a method for cleaning a surface of asubstrate.

BACKGROUND

Integrated circuits are formed in and on silicon and other semiconductorsubstrates. In the case of single crystal silicon, substrates are madeby growing an ingot from a bath of molten silicon, and then sawing thesolidified ingot into multiple substrates. An epitaxial silicon layermay then be formed on the monocrystalline silicon substrate to form adefect free silicon layer that may be doped or undoped. Semiconductordevices, such as transistors, may be manufactured from the epitaxialsilicon layer. The electrical properties of the formed epitaxial siliconlayer are generally better than the properties of the monocrystallinesilicon substrate.

Surfaces of the monocrystalline silicon and the epitaxial silicon layerare susceptible to contamination when exposed to typical substratefabrication facility ambient conditions. For example, a native oxidelayer may form on the monocrystalline silicon surface prior todeposition of the epitaxial layer due to handling of the substratesand/or exposure to ambient environment in the substrate processingfacility. Additionally, foreign contaminants such as carbon and oxygenspecies present in the ambient environment may deposit on themonocrystalline surface. The presence of a native oxide layer orcontaminants on the monocrystalline silicon surface negatively affectsthe quality of an epitaxial layer subsequently formed on themonocrystalline surface. It is therefore desirable to pre-clean thesubstrates in order to remove the surface oxidation and othercontaminants before epitaxial layers are grown on the substrates.

Conventional pre-clean processes are often carried out in a standalonevacuum process chamber having a substrate support pedestal. The topplate of the pedestal on which the substrate is supported is fabricatedfrom ceramic to prevent metal contamination resulting from substratecontact with metal surfaces. Because the ceramic plate is a poorconductor of heat, temperature control of the top surface of thepedestal in contact with the substrate is difficult, and the timerequired to stabilize the temperature of the substrate can beprohibitively long, which may undesirably increase substrate processingtime and the cost to process the substrate. In addition, some processeswill cycle the substrate temperature between two or more temperatures,and the impact of this stabilization time may be repeated multipletimes.

Therefore, there is a need in the art to for an improved substratesupport pedestal for use in a precleaning chamber.

SUMMARY

An improved substrate support pedestal assembly is described herein. Inone implementation, the substrate support pedestal assembly includes ashaft and a substrate support pedestal coupled to the shaft. Thesubstrate support pedestal includes an aluminum substrate support platehaving a top surface coated with a ceramic material. The substratesupport pedestal assembly may also include backside gas channels, whichcan be used to further improve coupling between a top surface of thesubstrate support pedestal and a substrate.

An improved processing chamber is described herein. In oneimplementation, the processing chamber includes a chamber body and apedestal assembly at least partially disposed within the chamber body.The pedestal assembly includes a substrate support pedestal to support asubstrate thereon during processing. The substrate support pedestalincludes a shaft and an aluminum substrate support plate mechanicallycoupled to the shaft and having a top surface coated with a ceramicmaterial.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations of the present disclosure, briefly summarized above anddiscussed in greater detail below, can be understood by reference to theillustrative implementations of the disclosure depicted in the appendeddrawings. It is to be noted, however, that the appended drawingsillustrate only typical implementations of this disclosure and aretherefore not to be considered limiting of its scope, for the disclosuremay admit to other equally effective implementations.

FIG. 1 is a cross-sectional view of a precleaning chamber in accordancewith one implementation of the present disclosure.

FIG. 2 is a cross-sectional view of a substrate support pedestalaccording to one embodiment.

FIG. 3 is a perspective view of the substrate support pedestal of FIG. 2.

FIG. 4 is a plot of time versus temperature of a substrate undergoingtemperature cycling in a chamber that employs a conventional substratesupport pedestal and a plot of temperature of a substrate undergoingtemperature cycling in a chamber that employs the substrate supportpedestal of FIGS. 2 and 3 .

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. The figures are not drawn to scale and may be simplifiedfor clarity. It is contemplated that elements and features of oneimplementation may be beneficially incorporated in other implementationswithout further recitation.

DETAILED DESCRIPTION

In semiconductor substrate processing, oxides are removed from a surfaceof a semiconductor substrate using a precleaning process. The cleaningprocess may include a plasma process performed within a precleaningchamber. The precleaning chamber includes a chamber body, a lidassembly, and a support assembly. The support assembly includes asubstrate support pedestal on which a substrate rests. The substratesupport pedestal and substrate may be moved vertically within a chamberbody by an actuator that elevates a shaft of the substrate supportpedestal. The substrate support pedestal may be elevated to a positionin close proximity to the lid assembly to elevate the temperature of thesubstrate being processed. The substrate is then lowered away from theelevated position to promote cooling of the substrate. This heating andcooling may be repeated over several cycles.

To facilitate rapid heating and cooling of the substrate, the substratesupport pedestal is fabricated essentially entirely from metal plates toenhance efficient heat transfer. The substrate support pedestal includesa substrate support plate coated on a top surface with a non-metallicmaterial, such as a ceramic, which prevents metal contamination of thesubstrate. Compared to related art substrate support plates madeentirely out of ceramic, the thin coating on the substrate support platesignificantly reduces the time needed to heat and cool the substrate.The substrate support pedestal further includes a number of underlyingmetal plates having various functions that are brazed together tofurther enhance and promote good thermal conductivity through thepedestal.

FIG. 1 is a cross sectional view of a precleaning processing chamber 100that is adapted to remove contaminants, such as oxides, from a surfaceof a substrate. Exemplary processing chambers that can be adapted toperform a reducing process include Siconi™ processing chambers,available from Applied Materials, Inc., of Santa Clara, California.Chambers from other manufacturers may also be adapted to benefit fromthe invention disclosed herein.

The processing chamber 100 may be particularly useful for performing athermal or plasma-based cleaning process and/or a plasma assisted dryetch process. The processing chamber 100 includes a chamber body 112, alid assembly 114, and a pedestal assembly 116. The lid assembly 114 isdisposed at an upper end of the chamber body 112, and the pedestalassembly 116 is at least partially disposed within the chamber body 112.A vacuum system can be used to remove gases from processing chamber 100.The vacuum system includes a vacuum pump 118 coupled to a vacuum port121 disposed in the chamber body 112. The processing chamber 100 alsoincludes a controller 102 for controlling processes within theprocessing chamber 100.

The lid assembly 114 includes a plurality of stacked componentsconfigured to provide precursor gases and/or a plasma to a processingregion 122 within the chamber 100. A first plate 120 is coupled to asecond plate 140. A third plate 144 is coupled to the second plate 140.The lid assembly 114 may be connected to a remote plasma source 124 togenerate plasma-byproducts that then pass through the remainder of thelid assembly 114. The remote plasma source 124 is coupled to a gassource 152 (or the gas source 152 is coupled directly to the lidassembly 114 in the absence of the remote plasma source 124). The gassource 152 may include helium, argon, or other inert gas that isenergized into a plasma that is provided to the lid assembly 114. Inalternate embodiments, the gas source 152 may include process gases tobe activated for reaction with a substrate in the processing chamber100.

The pedestal assembly 116 includes a substrate support pedestal 132 tosupport a substrate 110 thereon during processing. The substrate supportpedestal 132 is coupled to an actuator 134 by a shaft 136 which extendsthrough a centrally-located opening formed in a bottom of the chamberbody 112. The actuator 134 may be flexibly sealed to the chamber body112 by bellows (not shown) that prevent vacuum leakage around the shaft136. The actuator 134 allows the substrate support pedestal 132 to bemoved vertically within the chamber body 112 between one or moreprocessing positions, and a release or transfer position. The transferposition is slightly below the opening of a slit valve formed in asidewall of the chamber body 112 to allow the substrate 110 to berobotically transfer into and out of the processing chamber 100.

In some process operations, the substrate 110 may be spaced from a topsurface by lift pins to perform additional thermal processingoperations, such as performing an annealing step. The substrate 110 maybe lowered to place the substrate 110 directly in contact with thesubstrate support pedestal 132 to promote cooling of the substrate 110.

FIG. 2 is a cross-sectional detail view of the substrate supportpedestal 132. The substrate support pedestal 132 includes a substratesupport plate 200, a gas distribution plate 206, a base plate 208 and acap plate 214. Although the substrate support plate 200, the gasdistribution plate 206, the base plate 208 and the cap plate 214 aredescribed below as separate individual plates, it is it is contemplatedthat any one or more of the plates 200, 206, 208, 214 may be fabricatedas a single unitary component, for example by lost foam casting or 3Dprinting.

The substrate support plate 200 includes a top surface 202 forsupporting thereon the substrate 110 during processing, a side surface203, and a bottom surface 205. The substrate support plate 200 has athickness a between 0.1 inches to 0.75 inches. The substrate supportplate 200 is generally fabricated from a material having good thermallyconductivity, such as a metal, e.g., aluminum.

The substrate support plate 200 may include a first sub-plate 220 a of afirst diameter and a second sub-plate 220 b of a second diameter largerthan the first diameter to form a lip 221 about a periphery of thesecond sub-plate 220 b. The sub-plates 220 a, 220 b may be brazedtogether to ensure good heat transfer. Alternatively, the substratesupport plate 200 may have a unitary construction. The first diameter issubstantially the same or slightly less than a diameter of the substrate110. The second diameter is larger than the first diameter, and mayoptionally be sufficient to support a processing ring (not show)circumscribing the substrate 110.

The top surface 202 of the substrate support plate 200 defines thesubstrate-supporting surface of the pedestal 132. The top surface 202 iscovered with a ceramic coating 204 to prevent metal contamination of thesubstrate 110. Suitable ceramic coatings include aluminum oxide,aluminum nitride, silica, silicon, yttria, YAG, or other non-metalliccoating materials. The coating 204 has a thickness in the range of 50microns to 1000 microns. The substrate 110 is configured to be vacuumchucked against the coating 204 disposed on the top surface 202 duringprocessing. The ceramic coating 204 is not present on the side surface203 and the lip 221.

The substrate support plate 200 includes a plurality of vacuum passages250. The vacuum passages 250 extend through the substrate support plate200 exiting on the top and bottom surfaces 202, 205. Vacuum is appliedthrough the vacuum passages 250 to secure the substrate 110 to the topsurface 202. It is contemplated that the vacuum passages 250 mayberouted differently through the substrate support plate 200 and providethe same functionality. The vacuum passages 250 may also be connected toa gas source, such as Ar, He, or N2 to provide backside purge behind thesubstrate 110, keeping process gases away from the back of the substrate110, or to provide a backside gas to increase thermal conduction betweenthe pedestal 132 and the substrate 110.

The gas distribution plate 206 is disposed below the substrate supportplate 200. The gas distribution plate 206 has a top surface 207, a sidesurface 209, and a bottom surface 211. The top surface 207 of the gasdistribution plate 206 is mechanically coupled to the bottom surface 205of the substrate support plate 200. The gas distribution plate 206 ismade of a thermally conductive material, e.g., a metal such as aluminum.

To further promote heat transfer between the adjoining plates 200, 206,the top surface 207 of the gas distribution plate 206 is brazed to thebottom surface 205 of the substrate support plate 200. The ceramiccoating 204 is not present on the side surface 209 to promote furtherthermal response of the pedestal 132. The gas distribution plate 206 hasa thickness in the range of 0.1 inch to 0.75 inch. The gas distributionplate 206 further includes a plurality of gas passages 213 that arealigned with the vacuum passages 250 of the substrate support plate 200so that vacuum applied to the passages 213 is effectively provided tothe top surface 202. The vacuum passages 250 are coupled to vacuum lines(not shown) that are routed through the shaft 136. In an example, thegas distribution plate 206 may be divided into multiple zones to providedifferent purge flows or vacuum set points to different areas of thesubstrate support pedestal 132.

The base plate 208 is disposed below the gas distribution plate 206, andsandwiches the gas distribution plate 206 against the support plate 200.The base plate 208 has a top surface 215, a side surface 217, and abottom surface 219. The top surface 215 of the base plate 208 ismechanically coupled to the bottom surface 211 of the gas distributionplate 206. The base plate 208 has a thickness in the range of 0.1 inchesto 0.75 inches. The base plate 208 is fabricated from a thermallyconductive material, e.g., a metal such as aluminum. To further promoteheat transfer between adjoining plates 206, 208, the top surface 215 ofthe base plate 208 is brazed to the bottom surface 211 of the gasdistribution plate 206.

The base plate 208 may include a first sub-plate 226 a of a firstdiameter and a second sub-plate 226 b of a second diameter larger thanthe first diameter to form a lip 227 about a periphery of the secondsub-plate 226 b. The ceramic coating 204 is not present on the sidesurface 217 or the lip 227 to promote good heat transfer of the pedestalwith the surrounding environment.

A diameter of the gas distribution plate 206 may be equal to a diameterof the second sub-plate 220 a to align the outer perimeter of the gasdistribution plate 206 with the substrate support plate 200. A diameterof the gas distribution plate 206 may be equal to a diameter of thefirst sub-plate 226 a to align the outer perimeter of the gasdistribution plate 206 with the base plate 208. The base plate 208 has aplurality of cooling channels 210 formed therein for receiving a coolantfluid for cooling the substrate 110 through cooling channels 210. Thecoolant fluid may for through the channels 210 in direct contact withmaterial of the base plate 208, or through a conduit disposed in thechannels 210.

The substrate support pedestal 132 further includes a cap plate 214mechanically couple to and underlying the base plate 208 for sealing thechannels 210 within the base plate 208. The cap plate 214 has a topsurface 222 and a side surface 223. The cap plate 214 has a thickness inthe range of 0.1 inches to 0.75 inches. The cap plate 214 may befabricated from a thermally conductive material, such as a metal, e.g.,aluminum. A diameter of the cap plate 214 may be equal to a diameter ofthe second sub-plate 226 a to align the outer perimeter of the baseplate 208 with the cap plate 214. To further promote a heat transferbetween the adjoining plates 208, 214, the top surface 222 of the capplate 214 is brazed to the bottom surface 219 of the base plate 208. Theceramic coating 204 is not present on the side surface 223 to promotegood heat transfer of the pedestal with the surrounding environment

A fluid supply conduit 216 and a fluid return conduit 218 disposedthrough the shaft 136. The fluid supply conduit 216 is coupled to aninlet port (not shown) of the channels 210 formed in thermal base plate208, while the fluid return conduit 218 is coupled to an outlet port(not shown) of the channels 210 formed in the base plate 208. The fluidprovided through the conduits 216, 218 is circulating through thecooling channels 212 of the base plate 208 to provide efficienttemperature control of the pedestal 132.

FIG. 3 is a perspective view of the substrate support pedestal 132 ofFIG. 2 . As noted above, the top surface 202 of the substrate supportplate 200 is covered with a ceramic coating 204 to prevent metalcontamination of the substrate 110. The top surface 202 of the substratesupport pedestal 132 generally has a plurality of concentric gasdistribution channels 330 interconnected with radial distributionchannels 332 for receiving purge gas from the gas distribution plate 206through passages 250 in the gas distribution plate 206 (as shown in FIG.2 ). The ceramic coating 204 covers the plurality of concentric gasdistribution channels 330 and the radial distribution channels 332.

FIG. 4 is a plot 402 of time versus temperature of the substrate 110disposed in a processing chamber that employs a convention coolingpedestal to a plot 406 of temperature of the substrate 110 for aprocessing chamber, such as the chamber 100, that employs the substratesupport pedestal 132 of FIGS. 2 and 3 . As shown in FIG. 4 , the plot402 has relatively consistent temperature peaks of about 58° C. andlower troughs of about 42° C. Further, there is noticeable upward driftin temperature observed for the plot 406 versus the plot 402. The plot406 has peaks that begin at about 60° C. (significantly hotter than thepeaks of the plot 402) and drift upward over several cycles to about 63°C., illustrating very robust and repeatable temperature control with thesubstrate support pedestal 132 relative to the conventional pedestal.The substrate support pedestal 132 therefore heats and cools morereliably than a conventional pedestal.

While the foregoing is directed to implementations of the presentdisclosure, other and further implementations of the disclosure may bedevised without departing from the basic scope thereof.

What is claimed is:
 1. A substrate support pedestal assembly suitablefor use in semiconductor manufacturing, comprising: a shaft; a substratesupport pedestal coupled to the shaft, the substrate support pedestalcomprising an aluminum substrate support plate having a top surface anda bottom surface, the aluminum substrate support plate furthercomprising: vertical passages extending from the bottom surface to thetop surface of the aluminum substrate support plate, and wherein the topsurface is coated with a ceramic material, the vertical passagescomprising vacuum passages; a gas distribution plate in contact with thebottom surface of the aluminum substrate support plate, the gasdistribution plate comprising a plurality of gas passages aligned withthe vacuum passages; a plurality of concentric gas distribution channelsconfigured to receive gas through the vertical passages from the gasdistribution plate; and a plurality of radial distribution channelscoupled to the plurality of concentric gas distribution channels,wherein the ceramic material is disposed over the plurality ofconcentric gas distribution channels and the plurality of radialdistribution channels.
 2. The substrate support pedestal assembly ofclaim 1, wherein the ceramic material is aluminum oxide.
 3. Thesubstrate support pedestal assembly of claim 1, wherein the plurality ofradial distribution channels extend from an inner concentric channel ofthe plurality of concentric gas distribution channels to an outerconcentric channel of the plurality of concentric gas distributionchannels.
 4. The substrate support pedestal assembly of claim 3, thealuminum substrate support plate further comprising: an inner peripheryand an outer periphery circumscribing the inner periphery; and a lipextending outward below the top surface, the lip extending between theouter periphery and the inner periphery, wherein the ceramic materialextends to the inner periphery and solely coats the top surface, suchthat the lip is exposed and sides of the aluminum substrate supportplate are exposed and uncoated by the ceramic material.
 5. The substratesupport pedestal assembly of claim 1, wherein the gas distribution plateis divided into multiple zones to provide different purge flows orvacuum set points to different areas of the substrate support pedestal.6. The substrate support pedestal assembly of claim 1, wherein the topsurface of the substrate support pedestal has the plurality ofconcentric gas distribution channels interconnected with the pluralityof radial distribution channels for receiving purge gas from the gasdistribution plate through the plurality of gas passages in the gasdistribution plate.
 7. The substrate support pedestal assembly of claim6, wherein the ceramic material covers the plurality of concentric gasdistribution channels and the radial distribution channels.
 8. Thesubstrate support pedestal assembly of claim 1, wherein the substratesupport pedestal further comprises: a base plate brazed to a bottom ofthe gas distribution plate, the base plate having a plurality of coolingchannels formed therein for receiving a coolant fluid routed through theshaft.
 9. The substrate support pedestal assembly of claim 8, whereinthe gas distribution plate and the base plate are fabricated fromaluminum.
 10. The substrate support pedestal assembly of claim 8,wherein the substrate support pedestal further comprises: a cap platecoupled to the base plate and sealing the cooling channels formed in thebase plate.
 11. A processing chamber suitable for use in semiconductormanufacturing, comprising: a chamber body; and a pedestal assembly atleast partially disposed within a processing region of the chamber body,wherein the pedestal assembly includes a substrate support pedestal tosupport a substrate thereon during processing, the substrate supportpedestal comprising: a shaft; and an aluminum substrate support platehaving a top surface and a bottom surface, the aluminum substratesupport plate mechanically coupled to the shaft and comprising: verticalpassages extending from the bottom surface to the top surface of thealuminum substrate support plate, and wherein the top surface is coatedwith a ceramic material, the vertical passages comprising vacuumpassages; and a gas distribution plate in contact with the bottomsurface of the aluminum substrate support plate, the gas distributionplate comprising a plurality of gas passages aligned with the vacuumpassages; a plurality of concentric gas distribution channels configuredto receive gas through the vertical passages from the gas distributionplate; and a plurality of radial distribution channels coupled to theplurality of concentric gas distribution channels, wherein the ceramicmaterial is disposed over the plurality of concentric gas distributionchannels and the plurality of radial distribution channels.
 12. Theprocessing chamber of claim 11, wherein the ceramic material is aluminumoxide.
 13. The processing chamber of claim 11, wherein the plurality ofradial distribution channels extend from an inner concentric channel ofthe plurality of concentric gas distribution channels to an outerconcentric channel of the plurality of concentric gas distributionchannels.
 14. The processing chamber of claim 13, the aluminum substratesupport plate further comprising: an inner periphery and an outerperiphery circumscribing the inner periphery; and a lip extendingoutward below the top surface, the lip extending between the outerperiphery and the inner periphery, wherein the ceramic material extendsto the inner periphery and solely coats the top surface, such that thelip is exposed and sides of the aluminum substrate support plate areexposed and uncoated by the ceramic material.
 15. The processing chamberof claim 11, wherein the gas distribution plate is divided into multiplezones to provide different purge flows or vacuum set points to differentareas of the substrate support pedestal.
 16. The processing chamber ofclaim 11, wherein the top surface of the substrate support pedestal hasthe plurality of concentric gas distribution channels interconnectedwith the plurality of radial distribution channels for receiving purgegas from the gas distribution plate through the plurality of gaspassages in the gas distribution plate.
 17. The processing chamber ofclaim 16, wherein the ceramic material covers the plurality ofconcentric gas distribution channels and the radial distributionchannels.
 18. The processing chamber of claim 11, wherein the substratesupport pedestal further comprises: a base plate brazed to a bottom ofthe gas distribution plate, the base plate having a plurality of coolingchannels formed therein for receiving a coolant fluid routed through theshaft.
 19. The processing chamber of claim 18, wherein the gasdistribution plate and the base plate are fabricated from aluminum. 20.The processing chamber of claim 18, wherein the substrate supportpedestal further comprises: a cap plate coupled to the base plate andsealing the cooling channels formed in the base plate.